Complex carbohydrates, for purposes of this invention are defined as any polymer comprising more than two sugar moieties and would thus include such classes of and oliosaccharides. Polysaccharides include glycosaminoglycans and mannans whereas oligosaccharides are inclusive of sialylated sugars such as milk sugars.
Glycosaminoglycans can be obtained from numerous sources {e.g. rooster combs, trachea, umbilical cords, skin, articular fluids and certain bacteria such as Streptococci spp). Most glycosaminoglycans (hyaluronic acid, chondroitin sulfates A, B, and C, heparin sulfate, heparin, keratan sulfate, dermatan sulfate, etc.) are composed of repeating sugars such as non-sulfated N-acetylglucosamine, glucuronic acid and n-acetyl galactosamine (these are known as non-sulfated glycosaminoglycans) or polysulfated sugars (sulfated glycosaminoglycans).
Mannans are mannose-based polysaccharides which are normally extracted from plants. The most noteworthy is acemannan which is a beta 1,4-linked acetylated mannan extracted from the Aloe Vera plant (Aloe barbadensis Miller). This plant has been thought for centuries to have certain healing powers. Not until the 1980s was the active ingredient isolated and proven to have an effect on the immune system (see J. Pharm. Sci., 73 (1), January 1984).
Sialylated sugars are oligosaccharides which contain sialyl groups (e.g. sialic acid). They often contain fucose and may be significant components in the inflammatory process. Sialyl Lewis.sup.x and its derivatives are examples from this group (Tyrell et al, Proc. Natl. Acad. Sci. USA, 88, November 1991). At present, this oligosaccharide is so difficult to prepare/obtain that the cost ($4,600,000/g as listed by Oxford Glycosystems) limits research activities to determine its mechanism of action. Some of the milk sugars (also called hexaoses) are also incorporated in this general class of compounds. Examples of these are difucosyllacto-N-hexaose a and b, Disialyl-monofucosyllacto-N-hexaose, monofucosyllacto-N-hexsaose I, II, and II (obtainable from Oxford Glycosystems, Inc.).
Heparin, hyaluronic acid and chondroitin sulfate have been used therapeutically for several years. Heparin has been used for a number of years as an anticoagulant. Hyaluronic acid has been used therapeutically for several years as a replacement for the vitreous humor of the eye post surgery and, more recently, as replacement for joint fluid in arthritic joints. An extensive discussion of its various utilities is found in U.S. Pat. No. 4,141,973 to Balazs. The mode of action for hyaluronic acid injected directly into joints for treatment of arthritis has been proposed to be lubrication and replacement of the degraded joint fluid with highly viscous hyaluronic acid (see J. Bone Jt. Surg. 54A, 1972). High molecular weight (&gt;750,000 daltons) and high viscosity were reported to be critical. (For purposes of this patent, all molecular weights are expressed as daltons. The unit designation will not be added hereafter.)
In the 1980s, it was discovered that chondroitin sulfate, or polysulfated glycosaminoglycan (known by its commercial name as ADEQUAN) could be injected intramuscularly for reduction of pain and inflammation associated with arthrosis of horses. The mechanism of action of this glycosaminoglycan has been speculated to be inhibition of certain degradative enzymes present in the joint fluid which are up-regulated by trauma.
In 1989, it was discovered that intravenous, intramuscular or subcutaneous delivery of hyaluronic acid could reduce the pain of arthritis (U.S. Pat. No. 4,808,576 by Schultz et al) when the hyaluronic acid was delivered remote to the site of the arthritis (not into the joint). This patent specifically states that the hyaluronic acid is administered remote to the site, that the higher molecular weights are preferred for topical applications and that the hyaluronic acid must be of high purity (&gt;99% pure hyaluronic acid). No mention is made of hyaluronic acid in combination with essential oils or use of other macromolecules such as complex carbohydrates.
The importance of high molecular weight for effectiveness of hyaluronic acid in the treatment of arthritis is emphasized by Balazs (U.S. Pat. No. 4,141,973) and in a publication by Howard and McIlraith (see The Compendium, 15(3), March 1993) who summarize several clinical studies conducted to determine the most efficacious molecular weight range of hyaluronic acid injected intra-articularly to treat traumatic arthritis in horses. The conclusion from these studies is that hyaluronic acid with a molecular weight below 1.times.10.sup.6 is not as effective as hyaluronic acid with a molecular weight above this value. More recently, della Valle et al (U.S. Pat. No. 5,166,331) claimed that there are two distinct pharmacologically active molecular weight ranges of hyaluronic acid or salts thereof. These moieties are utilized separately (purified one from the other) and defined as 50,000-100,000 (Hylastine) and 500,000-730,000 (Hylectin). Hylastine is specified for use in wound healing while Hylectin is specified for use in ocular surgery.
Whereas Balazs (U.S. Pat. No. 4,141,973), Schultz (U.S. Pat. No. 4,808,576) and della Valle (U.S. Pat. No. 5,166,331) all specify use of highly purified hyaluronic acid and whereas Balazs (U.S. Pat. No. 4,141,973) discards the fractions containing hyaluronic acid or their salts having molecular weights less than 750,000; and whereas della Valle (U.S. Pat. No. 5,166,331) discards impurities having molecular weights less than 30,000 and does not use hyaluronic acid with molecular weights between 100,000 and 500,000 and, thus, specifies use of clearly-defined molecular weights of hyaluronic acid for topical or ocular use; and whereas Schultz prefers use of hyaluronic acid with a molecular weight between 1.2.times.10.sup.6 and 4.0.times.10.sup.6 in topical formulations, we have discovered that all molecular weights of hyaluronic acids or salts thereof and all purities of this polymer are useful in topical preparations when mixed with essential oils for the treatment of various medical problems. The low purity hyaluronic acid or salt thereof useful in this invention (&lt;98% pure hyaluronic acid) can be of a cosmetic grade which can contain up to 5% contaminants such as proteins, nucleic acids, teichoic acids and even endotoxins. Such material would not pass the owl monkey eye test used to select high purity hyaluronic acids and salts thereof (described by Balazs in U.S. Pat. No. 4.141.973) in that it would produce an inflammatory response in the eye. It also would not pass the horse joint injection test described by Schultz et al (U.S. Pat. No. 4,808,576). However, it does not produce a reaction when applied to the skin of mammals including humans, dogs, cats, horses, cattle, swine, rabbits, guinea pigs and mice.
Essential oils are natural components of plants which are extracted by various methods known to the art. They are generally very complex, containing numerous compounds (see Perfumer and Flavorist, 17, November/December 1992). More recently, some of the essential oils have been chemically synthesized. Most uses of these oils are as flavorings for foods and candies and as bath, cosmetic and perfume ingredients to provide pleasant aromas.
Some of the essential oils, also known as volatile oils, such as Rosemary Oil, Anise Oil, Cinnamon Oil, Clove Oil, Lemon Oil and Cardamom Oil have been shown to have limited antibacterial activity (see Elkhoully et al, 1980, Aust. J. Pharm. Sci., 9(3) September 1980 and Pharm. Acta Helv., 66(9-10) 1991). However, this activity was minimal when compared with a preservative used in current pharmaceuticals.
Several of the essential oils (i.e. Menthol, Eucalyptus Oil, Camphor, Peppermint Oil and Wintergreen Oil) are currently used in over-the-counter topical preparations such as BenGay, Mineral Ice, Flexall 454, etc. at concentrations as high as 30%. These topical medications claim pain relief but, according to FDA, act to relieve pain by producing a counterirritation, not by penetrating the skin and acting systemically to reduce inflammation and swelling which are the causes of pain. Also, these medications do not claim to reduce bruising, deep pain, itching, or induce wound healing. It has been noted by Williams and Barry (1989, Internat. J. Pharm., 57, 1989) that some essential oils such as chenopodium, eucalyptus, anise and ylang ylang oils penetrate the skin.
The inflammatory response is becoming better understood and has recently been summarized by Adams and Shaw (The Lancet, 343, Apr. 2, 1994). In their explanation, an adhesion cascade is stimulated when trauma occurs. This adhesion cascade is divided into four sequential steps of tethering, triggering, strong adhesion and motility. Tethering interactions are mediated by a family of three lectin-like carbohydrate-binding molecules (selectins). These interactions are strong enough to cause the leucocytes to roll along the blood vessel walls instead of flowing freely through such vessels, but not strong enough to cause these leucocytes to slow down. The triggering response is stimulated by factors such as cytokines and mediated by adhesion molecules called integrins. Integrins, by themselves, do not bind well to epithelium. However, when activated, integrins promote strong adhesion of the leucocyte to the epithelial surface. Leucocytes bind to the epithelial cells via their receptor sites such as CD44, CD31, etc. (see below). During strong adhesion, the interaction of these integrins with their ligands on the surface of the leucocytes are responsible for cessation of movement and flattening of the leucocyte. Finally, a process involving VCAM-1 and LFA-1 and other such integrins allows leucocytes to pass between endothelial cell junctions and into the tissue which has been traumatized. Collection of leucocytes at the site of trauma produces inflammation which is then followed by pain.
Previously, Shimitzu, et al (J. Immunol., 143, 1989) and Denning et al (J. Immunol. 144, 1990) determined that all leucocytes contain a receptor for hyaluronate which they named CD44. This receptor also binds chondroitin sulfate to a lesser extent and some other glycosaminoglycans. According to Munro et al (Am. J. Path, 141(6), December 1992) a ligand for E-selectin found on many or all leucocytes is a sialylated, polylactosamine containing a fucose moiety called Sialyl-Lewis.sup.x. This ligand seems to be specifically expressed during the process of inflammation and its blockage could be significant in inhibiting the inflammatory process. Other receptors which bind to various macromolecules and complex carbohydrates have also been identified.